And straightening



,giada New HENRY DISSTON, OF PHILADELPHIA, PENNSYLVANIA.

Letters Patent No. 86,286, dated Jan-nary 26, 1869.

IMPROVEMENT IN' DEVICE FOR lSIiIlVIU'LTAVIZElO'ILJ'SLY HARDENlING- ANDSTRAIG-TENING- CIRCUIAR-SAW BLADES.

The Schedule referred to :in these Letters Patent and making part o Ithe same.

`on the 13th day otAugust, 1867; and

It consists in submitting circular-saw and other steel blades, while ina heated state, and while being submerged in the hardening-composition,to a lpressure between rigid rods or bars, all of which is fullydescribed hereafter.

In order to enable others skilled in the art to apply my invention, lwill now proceed to describe the mode `of carryinldY the saine intoexeet, reference being had to npanying drawing, which forms a part ofthis specification, and in' which- Figure l is a 'ront view, partly inseetion,of my apparatus for simultaneously hardening and straighteningcircular-saw and other steel blades;

Figures 2 and 3, transverse sections of the saine on the line 1 2, iig.1, showing the working-parts in different positions; and

Figure 4, a sectional plan view on the line 3-4, iig. 3. Similar lettersrefer to similar parts throughout the several views.

Within a metal trough or vessel, A, and secured to one side of the same,are three or any other suitable number of inclined guides or ways, B,grooved on their inner edges, and narrowed at the top of the trough, asplainly seen in figs. 2, 3, and 4.

Directly opposite these inclined ways, and secured tothe other side ofthe trough, are straight upright bars, C (l C, which support a metaltraine-work, D, consisting of an edging, t ai, 'of dat metal, to whichis secured a number of vertical rods, b, placed atan equal distanceapart from each other. (See iig. l.)

A similar frame, D', is hinged to the lower edge of the frame D, in sucha'manner that it shall have a tendency to tall back from the latter, asindicated by thearrow in 2.

Three wedge-shaped bars, E, each of which has a projection, cg-adaptedto the grooves of theinclined ways B, are arranged to slide between thelatter and the hinged frame D', the bars bein g connected together atthe top by a cross-piece, Ii', so that they may be simultaneously'raised and lowered in the trough.

When these bars are elevated, the fra-me D is permitted to fall back, asshown in lig. 2; but,` by reason of their wedge-like shape and theinclined ways upon which they slide, the said bars force the hingedfranre toward the. fra me D, when they are lowered into the trough, asshownin tig. 3.

A bent plate, d, which is secured to each side of the central bar F,projects between the rods b of the frames' D and D', for a purposedescribed hereafter.

In using the apparatus, the trough A is filled, or nearly filled, withoil or other hardening-liquid, and the bars F are raised, aspseeu infigs. l and 2.

A circular-saw blade, X, while in a heated state, is then introducedbetween the iixed and hinged frames D and Dits lower edge resting uponthe bent plates c?, and its upper edge against the central bar F.

The wedge-shaped bars are'then suddenly released from thesuspension-chain, andpermitted to fall, with the blade, into the.trough, so as to submergethe saw? blade in the hardening-composition,the frames D and D' closing upon the blade simultaneously with itsdescent into the trough, so that, by the time the bars F have reachedthe 'limit of their downward movement, the blade is. firmly grpedbetween therods b b ofthe two frames, and thus held until'subrnitted,for a proper time, -to the action of the hardening-composition.

In order to prevent the wedge-shaped bars from descending too far intothe trough, the latter is provided at cach end with stops lt 71., whichare struck by rubber cushionsr z', seeured'to the opposite ends of thecrosspiece F, these cushions `serving,` to reduce the shock caused bythe sudden descent of the cross-piegeI upon the said stops.

In mytbrmer patent, of August 13, 1867, the sawblades were strengthened,while submitted to the hardching-process, by being pressed between flatplates of Inet-al, but, although this method answered well for narrowsaw-blades and thin strips of steel, I have found in practice, that forcil'cula1 sawblades, or other plates havingl a. large area, it isuncertain in its operation, inasmuch as the hardening-composition isprevented, by the pressure-plates, from coming in contact with thesurice of the metal.

'This objection, however, is entirely obviated by the use of' the tramesD and D', the rods l) eliectuallylstraightening the blades, andpreventing,` them from warping, and at the same time permitting the freepassage of the hardening-liquid to their entire surfaces.

Upon elevating the bars F, the hardened plate is raised from the troughby the plate d, upon which it rests, the frame D' falling back, asbefore described, and permittingr the withdrawal of the blade,and theintroduction ot a second, which is treated in the same manner.

I claim-as my invention, anddesireto secure by Letters Patentllie mode,substantially as herein described, of' simultaneously hardeninga-ndstraighteningcircular-saw blades, by submittingl them, while in a heatedstate, to a pressure between rigid bars or rods, while, at the sametime, they are submerged in the hardening-composition In testimonywhereof', I have signed my name to this specification, in the presenceof two subscribing witnesses.

HENRY DISSTON. Witnesses A. H. SHOEMAKER, WILLIAM A. STEEL.

